TIANJIN, Aug. 14 -- Guo Shengkun, Minister of Public Security, once again visited the blast site in Tianjin on Friday to direct rescue operations, urging all-out efforts to search and save lives.

Blasts ripped through a warehouse storing dangerous chemicals in Tianjin on Wednesday night, killing at least 50 people and injuring more than 700.

Guo, who is also a state councilor, said that saving lives must be prioritized in the rescue operations, as demanded by President Xi Jinping and Premier Li Keqiang.

He stressed that rescue operations must be conducted in an efficient and scientific way.

Guo said he was very gratified on knowing the successful rescue of a 19-year-old firefighter named Zhou Ti, and urged persistent efforts in searching and rescuing people.

Guo urged authorities to ensure the injured be treated in a timely and proper manner with the best medical resources.

He stressed expertise must be used to to quench the fire as early as possible and prevent secondary accidents.

Guo also called for psychological support and counseling service for the injured and family members of the victims.